How Do Betting Odds Work? Vig & Probability

Betting odds represent two things at once: your payout and the probability the sportsbook assigns to an outcome. Books shade their prices to build in a margin called the vig, so the implied probabilities of both sides add up to more than 100 percent. Beating the vig starts with taking the best number.

See odds as a price. Odds are the price of a bet. A -110 total means you pay a 10 percent premium to win 100, and that premium is how the book profits.
Find the implied probability. Convert each side's odds to a probability. If both sides sum to 105 percent, the extra 5 percent is the vig you must overcome.
Strip the vig for the fair price. A no-vig calculator removes the margin to show the market's fair odds, which is your benchmark for whether a price is good.
Take the best available number. Because every book prices differently, the highest plus or lowest minus you can find is a direct, repeatable edge.

How the vig works

On a two-way market priced -110 / -110, both sides' implied probabilities add to about 105 percent, not 100. That extra 5 percent is the vig. Bet 110 to win 100 on each side and the book keeps the difference regardless of who wins. Over thousands of bets, that margin is the house edge you are fighting, which is why the price you take matters as much as the pick.

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Why line shopping beats the vig

If one book has your side at -110 and another at -105, taking -105 lowers the vig you pay on every bet. Do that consistently and you claw back a chunk of the house edge without handicapping a single game. That is why sharp bettors hold accounts at several books and always shop the line.

Frequently asked questions

What is the vig?

The vig, or juice, is the margin a sportsbook builds into its odds. It is why the implied probabilities of both sides of a bet add up to more than 100 percent.

Do odds show the real probability of an outcome?

No. Odds show the book's shaded probability, inflated by the vig. Strip the vig with a no-vig calculator to see the fair price.

Related guides

How to read betting odds: American betting odds use a plus or minus sign.
How to find value bets: A value bet is one where the odds you can get are better than the fair, no-vig probability of the outcome.
How to make money sports betting: Making money in sports betting is not about picking more winners, it is about price and discipline.

Keep going

No-Vig Calculator →What is the vig? →Odds Screen tool →What is closing line value? →Read betting odds →Find value bets →Make money betting →Bet a parlay →Bet on college football →Bet on the NHL →All betting guides →

21+. For entertainment and educational purposes, not financial advice. If gambling stops being fun, take a break. 1-800-GAMBLER. Regulated US books only.